ARM Accredited engineer (EN0-001) Free Practice Test

Question 1

Which of the following register values would cause an unaligned access when the instruction LDRH r0, [r1] is executed?

A. R0=0x101. R1=0x1003

B. R0=0x100, R1 =0x1000

C. R0=0x101, R1=0x1002

D. R0=0x100, R1=0x1002

Correct Answer: A

Question 2

If a 16-bit Thumb instruction causes a Data Abort, which instruction would return from the handler to the instruction after the one that caused the data abort?

A. SUBS PC, LR-#4

B. SUBS PC, LR, #8

C. SUBS PC. LR

D. SUBS P LR, #6

Correct Answer: D

Question 3

When using an Operating System, which instruction is used by user code to request a service from the kernel?

A. SRSFD

B. SVC

C. RFEFD

D. BLX

Correct Answer: B

Question 4

Capturing processor execution trace is characterized as being:

A. Not intrusive on normal processor operation.

B. Influenced by breakpoints.

C. Inaccurate regarding code execution history.

D. Intrusive on normal processor operation.

Correct Answer: A

Question 5

The following pseudocode sequence shows a flag being set to indicate that new data is ready to be read by another thread:
data = 123;
ready = true;
Assuming that the reader threads may execute on any other core of a multicore system, which of the following is the most efficient memory barrier to place between the two writes to prevent them being observed in the opposite order?

A. DSBST

B. DMBSY

C. DMBST

D. DSBSY

Correct Answer: C

Question 6

According to the EABI. what would the C size of () operator return when given the following structure?

A. 20

B. 19

C. 28

D. 24

Correct Answer: D

Question 7

When timing a critical function for an algorithm, using platform time functions such as get time of day (), the result is unpredictable; there is significant variance in the measured time between different runs of the benchmark. Which of the following strategies would improve the accuracy of the measurement?

A. Break the algorithm into smaller pieces and time them individually

B. Add some code with a known overhead to the algorithm to make it run slower, and remove the overhead afterwards

C. Run the code on a software model of the platform and collect the results on that system

D. Time multiple executions of the algorithm and average the result

Correct Answer: D

Question 8

In a multi-processor system, there are four processors numbered 0, 1, 2 and 3. The state of the processors is as follows:
-CPU 0 and 1 are sleeping in low-power state following a WFI instruction. . CPU 2 is executing program code. -CPU 3 is sleeping in low-power state following a WFE instruction.
CPU 2 executes a SEV instruction. What is the effect on the system?

A. CPU 0: executing, CPU 1: executing, CPU 2: executing. CPU 3: executing

B. CPU 0: sleeping, CPU 1: sleeping. CPU 2: executing. CPU 3: executing

C. CPU 0: sleeping, CPU 1: sleeping. CPU 2: sleeping, CPU 3: executing

D. CPU 0: executing, CPU 1: executing. CPU 2: executing. CPU 3: sleeping

Correct Answer: B

Question 9

Which TWO of the following options can the ARM Compiler (armcc) directive__packed be used for? (Choose two)

A. To tell the compiler that an object can be on an unaligned address

B. To tell the compiler to produce code of minimum size

C. To tell the compiler not to perform padding inside structures

D. To tell the compiler to use the v6 SIMD pack/unpack instructions

E. To tell the compiler to use only Thumb code

Correct Answer: A,C

Question 10

Which of the following statements regarding Strongly-ordered memory is architecturally FALSE?

A. A write to Strongly-ordered memory is permitted to complete before it reaches the peripheral or memory component accessed by the write

B. The number and size of accesses to Strongly-ordered memory must be the same as that specified by the program

C. Address locations marked as Strongly-ordered memory are never held in a cache

D. The architecture does not permit speculative data accesses to Strongly-ordered memory

Correct Answer: A

Question 11

Printf statements could be used to achieve which of the following debug tasks?

A. Stop the processor at an interesting location in the code

B. Debug boot code, before a call to the C main() function

C. Observe changes to a local variable in a function

D. Capture a real-time trace of program execution

Correct Answer: C

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ARM Accredited engineer (EN0-001) Free Practice Test